<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
  <meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
  <style>
    body {
      margin: 0;
      padding: 0;
      overflow: hidden;
    }

    .city {
      width: 100%;
      position: fixed;
      bottom: 0px;
      z-index: 100;
    }

    .city img {
      width: 100%;
    }
  </style>
  <title>放烟花模拟</title>
</head>
<body onselectstart="return false">
<canvas id='cas' style="background-color:rgba(0,5,24,1)">浏览器不支持canvas</canvas>
<div class="city"><img src="city.png" alt=""/></div>
<img src="moon.png" alt="" id="moon" style="visibility: hidden;"/>
<div style="display:none">
  <div class="shape">新年快乐</div>
  <div class="shape">合家幸福</div>
  <div class="shape">HAPPY</div>
</div>
<audio src="boom.mp3" preload="auto"></audio>
<audio src="boom.mp3" preload="auto"></audio>
<audio src="boom.mp3" preload="auto"></audio>
<audio src="boom.mp3" preload="auto"></audio>
<audio src="boom.mp3" preload="auto"></audio>
<audio src="boom.mp3" preload="auto"></audio>
<audio src="shotfire.mp3" preload="auto"></audio>
<audio src="shotfire.mp3" preload="auto"></audio>
<audio src="shotfire.mp3" preload="auto"></audio>
<script>
  var canvas = document.getElementById("cas");
  var ocas = document.createElement("canvas");
  var octx = ocas.getContext("2d");
  var ctx = canvas.getContext("2d");
  ocas.width = canvas.width = window.innerWidth;
  ocas.height = canvas.height = window.innerHeight;
  var bigbooms = [];

  window.onload = function() {
    initAnimate()
  }

  function initAnimate() {
    drawBg();

    lastTime = new Date();
    animate();
  }

  var lastTime;
  function animate() {
    ctx.save();
    ctx.globalCompositeOperation = 'destination-out';
    ctx.globalAlpha = 0.1;
    ctx.fillRect(0, 0, canvas.width, canvas.height);
    ctx.restore();

    var newTime = new Date();
    if (newTime - lastTime > 200 + (window.innerHeight - 767) / 2) {
      var random = Math.random() * 100 > 2 ? true : false;
      var x = getRandom(canvas.width / 5, canvas.width * 4 / 5);
      var y = getRandom(50, 200);
      if (random) {
        var bigboom = new Boom(getRandom(canvas.width / 3, canvas.width * 2 / 3), 2, "#FFF", {x: x, y: y});
        bigbooms.push(bigboom)
      }
      else {
        var bigboom = new Boom(getRandom(canvas.width / 3, canvas.width * 2 / 3), 2, "#FFF", {
          x: canvas.width / 2,
          y: 200
        }, document.querySelectorAll(".shape")[parseInt(getRandom(0, document.querySelectorAll(".shape").length))]);
        bigbooms.push(bigboom)
      }
      lastTime = newTime;
    }

    stars.foreach(function() {
      this.paint();
    })

    drawMoon();

    bigbooms.foreach(function(index) {
      var that = this;
      if (!this.dead) {
        this._move();
        this._drawLight();
      }
      else {
        this.booms.foreach(function(index) {
          if (!this.dead) {
            this.moveTo(index);
          }
          else if (index === that.booms.length - 1) {
            bigbooms.splice(bigbooms.indexOf(that), 1);
          }
        })
      }
    });

    raf(animate);
  }

  function drawMoon() {
    var moon = document.getElementById("moon");
    var centerX = canvas.width - 200, centerY = 100, width = 80;
    if (moon.complete) {
      ctx.drawImage(moon, centerX, centerY, width, width)
    }
    else {
      moon.onload = function() {
        ctx.drawImage(moon, centerX, centerY, width, width)
      }
    }
    var index = 0;
    for (var i = 0; i < 10; i++) {
      ctx.save();
      ctx.beginPath();
      ctx.arc(centerX + width / 2, centerY + width / 2, width / 2 + index, 0, 2 * Math.PI);
      ctx.fillStyle = "rgba(240,219,120,0.005)";
      index += 2;
      ctx.fill();
      ctx.restore();
    }

  }

  Array.prototype.foreach = function(callback) {
    for (var i = 0; i < this.length; i++) {
      if (this[i] !== null) callback.apply(this[i], [i])
    }
  }

  var raf = window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame || function(callback) {
        window.setTimeout(callback, 1000 / 60);
      };

  canvas.onclick = function() {
    var x = event.clientX;
    var y = event.clientY;
    var bigboom = new Boom(getRandom(canvas.width / 3, canvas.width * 2 / 3), 2, "#FFF", {x: x, y: y});
    bigbooms.push(bigboom)
  }

  var Boom = function(x, r, c, boomArea, shape) {
    this.booms = [];
    this.x = x;
    this.y = (canvas.height + r);
    this.r = r;
    this.c = c;
    this.shape = shape || false;
    this.boomArea = boomArea;
    this.theta = 0;
    this.dead = false;
    this.ba = parseInt(getRandom(80, 200));

    var audio = document.getElementsByTagName("audio");
    for (var i = 0; i < audio.length; i++) {
      if (audio[i].src.indexOf("shotfire") >= 0 && (audio[i].paused || audio[i].ended)) {
        audio[i].play();
        break;
      }
    }
  }
  Boom.prototype = {
    _paint: function() {
      ctx.save();
      ctx.beginPath();
      ctx.arc(this.x, this.y, this.r, 0, 2 * Math.PI);
      ctx.fillStyle = this.c;
      ctx.fill();
      ctx.restore();
    },
    _move: function() {
      var dx = this.boomArea.x - this.x, dy = this.boomArea.y - this.y;
      this.x = this.x + dx * 0.01;
      this.y = this.y + dy * 0.01;

      if (Math.abs(dx) <= this.ba && Math.abs(dy) <= this.ba) {
        if (this.shape) {
          this._shapBoom();
        }
        else this._boom();
        this.dead = true;
      }
      else {
        this._paint();
      }
    },
    _drawLight: function() {
      ctx.save();
      ctx.fillStyle = "rgba(255,228,150,0.3)";
      ctx.beginPath();
      ctx.arc(this.x, this.y, this.r + 3 * Math.random() + 1, 0, 2 * Math.PI);
      ctx.fill();
      ctx.restore();
    },
    _boom: function() {
      var fragNum = getRandom(100, 300);
      var style = getRandom(0, 10) >= 5 ? 1 : 2;
      var color;
      if (style === 1) {
        color = {
          a: parseInt(getRandom(128, 255)),
          b: parseInt(getRandom(128, 255)),
          c: parseInt(getRandom(128, 255))
        }
      }

      var fanwei = fragNum;
      var audio = document.getElementsByTagName("audio");
      for (var i = 0; i < audio.length; i++) {
        if (audio[i].src.indexOf("boom") >= 0 && (audio[i].paused || audio[i].ended)) {
          audio[i].play();
          break;
        }
      }
      for (var i = 0; i < fragNum; i++) {
        if (style === 2) {
          color = {
            a: parseInt(getRandom(128, 255)),
            b: parseInt(getRandom(128, 255)),
            c: parseInt(getRandom(128, 255))
          }
        }
        var a = getRandom(-Math.PI, Math.PI);
        var x = getRandom(0, fanwei) * Math.cos(a) + this.x;
        var y = getRandom(0, fanwei) * Math.sin(a) + this.y;
        var radius = getRandom(0, 2)
        var frag = new Frag(this.x, this.y, radius, color, x, y);
        this.booms.push(frag);
      }
    },
    _shapBoom: function() {
      var that = this;
      putValue(ocas, octx, this.shape, 5, function(dots) {
        var dx = canvas.width / 2 - that.x;
        var dy = canvas.height / 2 - that.y;
        for (var i = 0; i < dots.length; i++) {
          color = {a: dots[i].a, b: dots[i].b, c: dots[i].c}
          var x = dots[i].x;
          var y = dots[i].y;
          var radius = 1;
          var frag = new Frag(that.x, that.y, radius, color, x - dx, y - dy);
          that.booms.push(frag);
        }
      })
    }
  }

  function putValue(canvas, context, ele, dr, callback) {
    context.clearRect(0, 0, canvas.width, canvas.height);
    var img = new Image();
    if (ele.innerHTML.indexOf("img") >= 0) {
      img.src = ele.getElementsByTagName("img")[0].src;
      imgload(img, function() {
        context.drawImage(img, canvas.width / 2 - img.width / 2, canvas.height / 2 - img.width / 2);
        dots = getimgData(canvas, context, dr);
        callback(dots);
      })
    }
    else {
      var text = ele.innerHTML;
      context.save();
      var fontSize = 200;
      context.font = fontSize + "px 宋体 bold";
      context.textAlign = "center";
      context.textBaseline = "middle";
      context.fillStyle = "rgba(" + parseInt(getRandom(128, 255)) + "," + parseInt(getRandom(128, 255)) + "," + parseInt(getRandom(128, 255)) + " , 1)";
      context.fillText(text, canvas.width / 2, canvas.height / 2);
      context.restore();
      dots = getimgData(canvas, context, dr);
      callback(dots);
    }
  }

  function imgload(img, callback) {
    if (img.complete) {
      callback.call(img);
    }
    else {
      img.onload = function() {
        callback.call(this);
      }
    }
  }

  function getimgData(canvas, context, dr) {
    var imgData = context.getImageData(0, 0, canvas.width, canvas.height);
    context.clearRect(0, 0, canvas.width, canvas.height);
    var dots = [];
    for (var x = 0; x < imgData.width; x += dr) {
      for (var y = 0; y < imgData.height; y += dr) {
        var i = (y * imgData.width + x) * 4;
        if (imgData.data[i + 3] > 128) {
          var dot = {x: x, y: y, a: imgData.data[i], b: imgData.data[i + 1], c: imgData.data[i + 2]};
          dots.push(dot);
        }
      }
    }
    return dots;
  }

  function getRandom(a, b) {
    return Math.random() * (b - a) + a;
  }


  var maxRadius = 1, stars = [];
  function drawBg() {
    for (var i = 0; i < 100; i++) {
      var r = Math.random() * maxRadius;
      var x = Math.random() * canvas.width;
      var y = Math.random() * 2 * canvas.height - canvas.height;
      var star = new Star(x, y, r);
      stars.push(star);
      star.paint()
    }

  }

  var Star = function(x, y, r) {
    this.x = x;
    this.y = y;
    this.r = r;
  }
  Star.prototype = {
    paint: function() {
      ctx.save();
      ctx.beginPath();
      ctx.arc(this.x, this.y, this.r, 0, 2 * Math.PI);
      ctx.fillStyle = "rgba(255,255,255," + this.r + ")";
      ctx.fill();
      ctx.restore();
    }
  }

  var focallength = 250;
  var Frag = function(centerX, centerY, radius, color, tx, ty) {
    this.tx = tx;
    this.ty = ty;
    this.x = centerX;
    this.y = centerY;
    this.dead = false;
    this.centerX = centerX;
    this.centerY = centerY;
    this.radius = radius;
    this.color = color;
  }

  Frag.prototype = {
    paint: function() {
      // ctx.beginPath();
      // ctx.arc(this.x , this.y , this.radius , 0 , 2*Math.PI);
      ctx.fillStyle = "rgba(" + this.color.a + "," + this.color.b + "," + this.color.c + ",1)";
      ctx.fillRect(this.x - this.radius, this.y - this.radius, this.radius * 2, this.radius * 2)
    },
    moveTo: function(index) {
      this.ty = this.ty + 0.3;
      var dx = this.tx - this.x, dy = this.ty - this.y;
      this.x = Math.abs(dx) < 0.1 ? this.tx : (this.x + dx * 0.1);
      this.y = Math.abs(dy) < 0.1 ? this.ty : (this.y + dy * 0.1);
      if (dx === 0 && Math.abs(dy) <= 80) {
        this.dead = true;
      }
      this.paint();
    }
  }
</script>
</body>
</html>